<html>
<head>
    <meta charset="utf-8"/>
    <title></title>
    <style type="text/css">
        .cro{
            width: 200px;
            height: 200px;
            border: 1px solid #58C4E6;
            position: relative;
        }
        .cro_left_top,.cro_right_top,.cro_left_bottom,.cro_right_bottom{
            position: absolute;
            width: 20px;
            height: 20px;
            border: 1px solid #fff;
            z-index: 1;
            background: #fff;
        }
        .cro_left_top{
            top: -1px;
            left: -1px;
            border-radius:0px 0px 20px 0px;
            border-bottom: 1px solid #58C4E6;
            border-right: 1px solid #58C4E6;
        }
        .cro_right_top{
            top: -1px;
            right: -1px;
            border-radius:0px 0px 0px 20px;
            border-bottom: 1px solid #58C4E6;
            border-left: 1px solid #58C4E6;
        }
        .cro_left_bottom{
            left: -1px;
            bottom: -1px;
            border-radius:0px 20px 0px 0px;
            border-top: 1px solid #58C4E6;
            border-right: 1px solid #58C4E6;
        }
        .cro_right_bottom{
            right: -1px;
            bottom: -1px;
            border-radius:20px 0px 0px 0px;
            border-top: 1px solid #58C4E6;
            border-left: 1px solid #58C4E6;
        }
        .bottom-circle{
            width: 20px;
            height: 10px;
            border-radius: 10px 10px 0 0 ;
            background: red;

            position: absolute;
            z-index: 1;

            bottom: 0;
            left: 0;
        }

        .top-circle{
            width: 20px;
            height: 10px;
            border-radius: 0 0 10px 10px ;
            background: red;

            position: absolute;
            z-index: 1;

            top: 0;
            right: 0;
        }

    </style>
</head>
<body>
<div class="cro">
    <!--<div class="cro_left_top"></div>-->
    <!--<div class="cro_right_top"></div>-->
    <div class="cro_left_bottom"></div>
    <!--<div class="cro_right_bottom"></div>-->
    <!--<div class="bottom-circle"></div>-->
    <div class="top-circle"></div>
</div>
</body>
</html>